An existing piezoelectric power generation apparatus that generates electric power using a piezoelectric element has been proposed (for example, see paragraphs 0078 to 0080 and FIG. 12(a) in Patent Document 1).
FIG. 10 is a view for explaining an example of the configuration of an existing piezoelectric power generation apparatus 101 by reference to description in Patent Document 1 and is a side view in a state where a part of the configuration of the piezoelectric power generation apparatus 101 is excluded.
The piezoelectric power generation apparatus 101 as illustrated in FIG. 10 includes a pedestal 111, a coil spring 112, a rocking member 113, a first weight 114, a piezoelectric element 121, and a second weight 122. The pedestal 111 is formed into a disc-like shape and is fixed to a floor slab 131 as a vibrating body. One end of the coil spring 112 is jointed to the pedestal 111 and the other end thereof is jointed to the disc-like shape rocking member 113. The coil spring 112 supports the rocking member 113 on the pedestal 111 in a rockable manner. The first weight 114 is jointed to a lower portion of the rocking member 113. The piezoelectric element 121 is jointed to the rocking member 113 through the first weight 114. The second weight 122 is jointed to the first weight 114 through the piezoelectric element 121. The second weight 122, the piezoelectric element 121, and the first weight 114 are arranged at the inner side of winding of the coil spring 112. An electrode 121A is provided on a contact surface of the piezoelectric element 121 with the first weight 114. An electrode 121B is provided on a contact surface of the piezoelectric element 121 with the second weight 122.
When vibration in the direction perpendicular to the flat surface of the floor slab 131 is generated on the floor slab 131 with force such as external vibration, the vibration is transmitted to the rocking member 113 through the pedestal 111 and the coil spring 112, and the first weight 114 jointed to the rocking member 113 vibrates. Then, the vibration is transmitted to the second weight 122 through the piezoelectric element 121 and the second weight 122 also vibrates. In this case, compression stress and tensile stress repeatedly act on the piezoelectric element 121 from the first weight 114 and the second weight 122, and electric charges are generated on the piezoelectric element 121 with a piezoelectric effect. The generated electric charges are extracted through the electrodes 121A and 121B provided on the piezoelectric element 121.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2011-114884